Support devices known as unit curbs are commonly employed to mount air conditioners on an inclined roof of a building. The air conditioner itself is maintained on the level or in a horizontal attitude, and ducts extend between the air conditioner and the interior of the building to provide for air flow between the air conditioner and the building interior.
Air conditioners should be maintained on the level (in a horizontal attitude) to allow proper operation thereof. This presents difficulties for air conditioner installers since the pitch or degree of inclination of inclined roofs can vary over a considerable range.
It has been the practice to custom build unit curbs so that they can be utilized with roofs with a particular degree of inclination. That is, a particular unit curb is constructed to maintain the air conditioner at a level for a particular degree of incline.
A unit curb suitable for a given degree of roof inclination will not be suitable for another degree of roof inclination or pitch. Thus the unit curb either must be fabricated on a custom per job basis or many unit curbs designed for different roof inclines must be manufactured in advance and stored in relatively large quantities, greatly adding to costs.